1. Field of the Invention
A continuous procedure for the separation of substances in three phases is presented, especially of the organic contained in wastes coming from the solvent extraction processes.
2. Description of the Related Art
A great number of procedures for the separation of the organic from wastes is known, but most of them include an initial stage of settling to separate solids, thus an emulsion being obtained for the liquid components, or crud, which mainly includes two phases: an aqueous phase and an organic solvent phase, wherein this organic phase is separated by different techniques of emulsion destabilization using a series of chemical reagents, in addition to mechanical breakdown operations basically consisting in inducing an increase in the volumetric ratio of the dispersoid in order to achieve a critical ratio determining the destabilization of the emulsion, the coalescence of the particles which were scattered, being thus started.
Depending on various factors, such as the type of mineral, the leaching process used in the extraction process applied, the crud from a plant generally has several degrees of stability and according to this, the suitable destabilization process therefor must be applied in order to achieve a maximum recovery of solvent. The stability of crud depends on organic:acqueous and acqueous:organic emulsion ratio, the latter being the most unstable component.
In the procedure of the invention, on the contrary, the previous obtainment of crud is not required, thus allowing the direct processing of wastes, avoiding the usual stages of settling used to previously separate solids. This procedure is really a continuous three-phase separation: solid phase, light liquid phase (organic solvent), and heavy liquid phase (aqueous). The procedure makes use of the xe2x80x9cgravityxe2x80x9d principle for separating liquids; more accurately said, it considers the application of several xe2x80x9cGsxe2x80x9d to the particles to be separated (typically 2,000 G).
If the separation of three phases, light-liquid/heavy-liquid plus nonsoluble solids, is necessary, the centrifugal separators shall be operated in batches, since the nonsoluble solids saturate the solid chamber of this kind of devices. The procedure of the invention, on the contrary, allows a continuous separation of substances in three phases: light-liquid/heavy-liquid plus nonsoluble solids, allowing the continuous discharge of solids out of the system.
On the other hand, the conventional procedures and equipments cannot dynamically control the separation zone of light-liquid/heavy-liquid phases, the process having to be suspended in order to carry out the phase selectivity adjustments. This kind of control is not practical when substances are to be processed, which phase compositions are constantly changing. The invention, on the contrary, allows a dynamic control of the light-liquid/heavy-liquid separation zone through the radial variation of centripetal means at the outlet of the heavy liquid phase.
Due to the characteristics of the procedure of the invention, as it will be explained in greater detail hereinbelow, this allows the separation of a very wide range of wastes, from those in which nonsoluble solids present a specific weight greater than the organic and lower than the aqueous, to those in which the nonsoluble solids present specific weight greater than the organic and aqueous, being also able to process the wastes which are a combination of the two preceding types.
In order to better understand the process of the invention, the same will be described in greater detail through a preferred embodiment.